1. Field of the Invention
The invention relates to contact springs. More specifically, the invention pertains to a contact spring with a base spring which on one end has a connecting part for an electrical power cord and on the other has a contact part with at least two spring arms, and having a detent sleeve, seated on the base spring, as a detent-type aid in retaining the contact spring inside a surrounding housing.
2. Description of the Related Art
Contact springs of this kind are widely known are described for instance in German utility model DE-U 92 02 365. Such contact springs are used widely as plug connectors in the automotive field, among others. Typically, the contact spring comprises a base spring, from which two spring arms of a contact part extend integrally away on one end, and a contact pin can be inserted between the two spring arms. The other end of the base spring is adjoined by a connecting part for an electrical power cord.
By way of example, the connecting part can be a crimp connection with a conductor wire claw and an insulation claw, which are clamped onto an electrical power cord or its sheathing. In the contact spring described in the aforementioned reference, a detent sleeve, also called an overspring, is seated on the base spring. The function of the detent sleeve is essentially to increase the spring force of the contact spring, and by being embodied with one or more detent tongues, to enable a disconnectable locking of the contact spring in an associated contact chamber of a surrounding housing made of insulating material.
The detent sleeve as a rule comprises a material with good spring properties, while the base spring is made from a material with good electrical and thermal properties. The detent sleeve can for example be made from a sheet metal as a stamped and bent part. The base spring is preferably also a stamped and bent part, but because of the requisite good electrical properties it preferably comprises tin bronze or so-called spring bronze.
Plug connectors must often be dustproof and/or splashproof. To achieve such sealed-off plug connectors, it is possible to use so-called sealing plates, such as rubber plates. The contact springs must be passed through these sealing plates, which are disposed on the surrounding housing.
It has been found that the inserted sealing plates become damaged especially whenever the contact elements have to be passed through this sealing plate multiple times in both directions, as can be the case when the plug connector is repaired, for instance. The sealing plates do have openings through which the contact springs can be guided. However, to achieve adequate sealing, these openings are smaller in diameter than the contact springs, so that when the contact spring is pushed through these openings, the openings in the sealing plate necessarily widen and stretch.
However, the prior art contact springs are distinguished by sharp-edged elements, which injure the sealing plate especially when the contact spring is pulled out of the contact chamber. Examples of these sharp-edged elements are first the detent tongue, provided in the conventional contact springs, on the detent sleeve and, if present, a sharp-edged polarizing tab bent at right angles out of a side wall of the detent sleeve.